Exercise device

ABSTRACT

The present invention relates to an exercise device to simulate a leg swing motion. The device comprises a frame, a longitudinal guide supported by the frame, and a moveable body reciprocally moveable along the guide. The moveable body has a pivot axis defined thereon. A swing arm is pivotally coupled to the moveable body about the pivot axis such that the moveable body moves rearwardly when the swing arm swings forwardly by a forwardly leg swing motion and the moveable body moves forwardly when the swing arm swings rearwardly by a rearwardly leg swing motion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an exercise device, and particularlyrelates to an exercise device with the purpose of strengthening legmuscles, hip joints, and muscle groups of the waist.

2. Description of Related Art

“Hip extension machine hip”, “flexing machines” and etc. are known asexercise devices for working leg muscles and muscle groups of the waistin a standing posture. With these exercise devices, a swing arm rotationfulcrum is fixed.

However, with exercise devices where the arm rotation fulcrum is a fixedtype, there is the drawback that the range of movement of the hip jointsis restricted. Further, with exercise devices where the rotation fulcrumis fixed, swinging of the arm traces a locus that is part of a circulararc. When the arm travels along such a circular arcuate path, there isrisk involved in that a relatively strong load is placed on the waistthat may cause the waist to be damaged as the arms are lifted up from avertical position to the horizontal.

In recent years, it has been recognized that exercising of the psoasmajor not only improves running ability but can also bring aboutimprovements in overall sports performance. For example, it has beenreported that from the results of a cross sectional view of an abdomentaken using Magnetic Resonance Imaging (MRI), short distance athleteshave a psoas major of a larger cross-sectional area, and there is a highcorrelation between substantial running ability and the area of thecross-section of the psoas major. Further, it has also been reportedthat it is easy for middle-aged to older people with a psoas major of asmaller cross-sectional area to become bedridden (Shinya Kuno: “Simplemuscle exercise for preventing people from becoming bedridden”), JapanBroadcasting Publishing Co. Ltd., 2002). Working of the psoas major cantherefore be confirmed to be important not just for athletes, but forthe elderly and the infirm.

Further, it has been reported that the use of “knee/waist same side typeactions” is effective as a way of using your body for improving sportsperformance (Kando Kobayashi: “creating sports actions to increaserunning performance”, Published by Kyorin-Shoin Publishers, 2001). A“knee/waist same side type action” is based on moving the waist of thesame side to the front while drawing out your leg to the front. At thistime, working of the pelvis, lumbar vertebrae, and the muscles locateddeep to the abdomen (such as the psoas major and iliacus, togethercalled the iliopsoas) connecting part of the thoracic vertebrae (twelfththoracic vertebrae) and the thighbone is extremely important. However,study of “knee/waist same side type actions” is difficult depending onthe person.

In the related art, with a “hip extension machine” and “hip flexingmachine”, it is not possible to effectively exercise the muscles locateddeep to the abdomen such as the psoas major and the iliacus. Further,supplementary exercise and training drills are also employed with theobject of strengthening psoas major but exercise equipment capable ofeffectively working psoas major have yet to be developed.

SUMMARY OF THE INVENTION

It is therefore the object of the present invention to provide anexercise device capable of effectively working the muscles located deepto the abdomen such as the psoas major and the iliacus.

A further object of the present invention is to provide an exercisedevice that does not place unnecessary loads on the waist.

The present invention relates to an exercise device where a leg isplaced on a swing arm provided so as to be able to swing forwardly andrearwardly via a fulcrum of rotation so that the leg is lifted upforwardly and rearwardly while the swing arm is swung forwardly andrearwardly. The fulcrum of rotation of the swing arm is reciprocallymoveable forwardly and rearwardly such that the fulcrum of rotationmoves rearwardly when the swing arm swing forwardly and the fulcrum ofrotation moves forwardly when the swing arm swings rearwardly.

In a preferred mode, the fulcrum of rotation of the swing arm is coupledto a moveable body capable of reciprocal movement forwardly andrearwardly. Preferably, the exercise device is provided with a forwardlyand rearwardly extending guide member, and the moveable body is guidedby the guide member so as to move forwardly and rearwardly.

In a preferred mode, swinging of a swing arm and movement of a movingbody forwardly and rearwardly are in synchronism. The exercise device ispreferably comprised of detecting means for detecting swinging of theswing arm, drive means for moving the moveable body, and control meansfor controlling movement of the moving body by the drive means based oninformation from the detecting means. Swinging of the swing arm andforwardly and rearwardly movement of the moveable body are thensynchronized as a result of the control means controlling the drivemeans. The swing arm may also swing via a rotational shaft, with thedetecting means detecting the angle and speed of the rotational shaft.

It is also possible to provide load applying means for resistingrotation of the swing arm at the moveable body. As a result, while thefulcrum of rotation of the swing arm moves forwardly and rearwardly, theload applying means therefore does not hinder movement of the fulcrum ofrotation.

It is also possible to adjust the position of the fulcrum of rotation ofthe swing arm in the height direction. In one mode, the guide member isconstructed so as to be freely moveable in the height direction.Adjustment of the position in the height direction of the fulcrum ofrotation of the swing arm is then carried out by adjusting the height ofthe guide member guiding the moveable body provided at the fulcrum ofrotation.

By adopting a configuration where the rotational shaft of the swing armmoves in a horizontal direction forwardly and rearwardly in line withthe angle of rotation of the swing arm, the present invention achievesthe following results. First, it is possible to ensure the size of therange of operation of the leg and trunk containing the hip joints,pelvis and thoracic vertebrae. In the event that the fulcrum of rotationof the prior art is fixed, the locus of movement of the swing arm tracesa circular arc taking the length of the swing arm as a radius. In thisrespect, with the apparatus of the present invention, the path of travelof the swing arm can be made to be a U-shape by having the fulcrum ofrotation of the swing arm move forwardly and rearwardly insynchronization with swinging of the swing arm forwardly and rearwardly.Giving a more detailed description, according to the exercise device ofthe present invention, with the swinging of the swing arm forwardly andrearwardly, a pad portion restraining the leg of the user travels alonga U-shaped path of travel with the position of a vertical posture beingthe bottom. As a result of the pad portion traveling along a U-shapedpath of travel, an action point (position of the pad) moves at aposition relatively close to the body when the leg is raised high.Because of this, there is no localized load on the waist and muscles. Itis therefore possible to perform exercise that strengthens the muscularpower of the trunk and legs with the leg and waist together.

By performing a forwardly and rearwardly swinging operation of the legtaking the leg and waist together, the exercise device of the presentinvention is capable of working leg muscles, gluteal muscles such as themusculus gluteus maximus and the musculus gluteus minimums, and themuscles located deep to the abdomen such as the psoas major and theiliacus. According to the device of the present invention, it ispossible to effectively strengthen the muscles such as the psoas majorand the iliacus by working the leg and the waist at the same time in thesame direction.

According to the exercise device of the present invention, it ispossible to effectively work the muscle groups of the legs and waistacross a broad range of movement centered on the hip joints. It is alsopossible for not only athletes but frail and elderly people to use thisapparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of the whole of an exercise device of the presentinvention;

FIG. 2 is a side view of the whole of an exercise device of the presentinvention;

FIG. 3 is a plan view of the whole of an exercise device of the presentinvention;

FIG. 4 is a side view of the whole of the exercise device showing astate where the swing arms are swung up forwardly as a result ofswinging up the legs forwardly;

FIG. 5 is a plan view of the whole of the exercise device showing astate where the swing arms are swung up forwardly as a result ofswinging up the legs forwardly;

FIG. 6 is a side view of the whole of the exercise device showing astate where the swing arms are swung up rearwardly as a result ofswinging up the legs rearwardly;

FIG. 7 is a plan view of the whole of the exercise device showing astate where the swing arms are swung up rearwardly as a result ofswinging up the legs rearwardly;

FIG. 8 is a view showing an internal configuration of a moveable body;

FIG. 9 is an outline front view of the exercise device of the presentinvention and is analogous to FIG. 1;

FIG. 10 is an outline side view of the exercise device of the presentinvention and is analogous to FIG. 2;

FIGS. 11A, 11B and 11C are views illustrating the relationship betweenswinging forwardly and rearwardly of the swing arm and movement of thefulcrum of rotation of the swing arm; and

FIG. 12 is a view illustrating control of the exercise device of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description is given of the present invention based on taking astanding operation-type exercise device as an embodiment. FIG. 1 to FIG.3 are an overall front view, overall side view, and overall plan view ofthe present invention. An exercise device has a box-shaped frame bodycomprised of a pair of front vertical frames 1, a pair of rear verticalframes, a plurality of lateral frames 3, 4, 5 and 6 linking the bottomends and top ends of the vertical frames 1 and 2 from the front to rear,and the left to right, a pair of vertical frames 7 linking between thefront lateral frames 3 in a vertical direction, and a pair of lateralframes 8 linking between the front and rear lateral frames forwardly andrearwardly.

A pair of left and right front posts 9 and a pair of left and right rearposts 10 stand up in parallel with the vertical frames 1 and 2 betweenforwardly and rearwardly extending the upper and lower lateral frames 5and 6. Guide members 11 extending horizontally forwardly and rearwardlyare provided between the posts 9 and 10 at the left side and right siderespectively. Moveable bodies 12 are provided in a manner capable ofmoving horizontally forwardly and rearwardly on the guide members 11.

The guide member 11 comprises an LM guide, and the moveable body 12 isfixed to a slider of the LM guide via a lower end part. A ball screw 14is then driven by a servo motor 13, and the moveable body 12 isreciprocally driven horizontally forwardly and rearwardly. Thehorizontally extending LM guide constituting the guide member 11 isfixed and horizontally supported at a forward end part and a rear endpart by a support member 15 provided at side surfaces of the forwardposts 9 and rearward posts 10. The support member 15 is linked to posts9, 10 in a state where vertical movement is possible using verticallyextending LM guides 16 provided at side surfaces of the forward posts 9and rearward posts 10. The LM guide 16 is made to extend up and down bydriving of an electric actuator 17 employing a motor so as to cause thesupport members 15 to move upwardly and downwardly. This enables thevertical position of the moveable body 12 to be adjusted. Movement ofthe moveable body 12 forwardly and rearwardly, and upwardly anddownwardly is driven by driving devices 13, 14 and 17 receivinginstructions from a controller 28. The speed and distance of forwardlyand rearwardly movement of the moveable body 12 can be adjusted usingthe controller 28. Means for guiding the moveable body 12 forwardly andrearwardly and means for driving the guide means are not limited to thatshown in the drawings. For example, it is possible for the moveable body12 to be made to move horizontally forwardly and rearwardly by utilizinga rack and pinion, or to cause the moveable body 12 to move horizontallyforwardly and rearwardly using a link mechanism.

The moveable body 12 is provided with a swing arm 18 capable of swingingforwardly and rearwardly. The swing arm 18 is coupled to a movable body12 so as to swing freely like a pendulum forwardly and rearwardly takingan upper end side as a fulcrum of rotation. The swing arm 18 is providedwith a horizontally extending pad 19 at lower end thereof. The pad 19extends orthogonally with a swing direction of the swing arm 18. Theattaching position of the pad 19 with respect to the swing arm 18 iscapable of being adjusted in a longitudinal direction of the swing arm18. Further, a support arm 20 is attached to the swing arm 18. Thesupport arm 20 is provided with a horizontally extending pad 19extending orthogonally with a swing direction of the swing arm 18. Thesupport arm 20 is coupled to the swing arm 18 in such a manner that thedirection of extension of the support arm 20 maintains an angle withrespect to the direction of extension of the swing arm 18, with each pad19 extending in an opposed manner at a prescribed spacing. The attachingposition of the support arm 20 with respect to the swing arm 18 iscapable of being adjusted in a longitudinal direction of the swing arm18. At the time of use, the leg is sandwiched between the pad 19 of theswing arm 18 and the pad 19 of the support arm 20, then swinging theswing arm 18 by swinging the leg forwardly or rearwardly. A descriptionis given of a leg placing section having the swing arm 18 and thesupport arm 19 but the configuration of the leg placing section is by nomeans limited to that shown in the drawings, provided that it ispossible for a user to place their leg on a swing arm so that the legcan be lifted up forwardly and rearwardly while swinging the swing armforwardly and rearwardly.

A moveable body 12 comprises a box having a hollow section. The moveablebody 12 is provided with a rotational shaft 21 (extending orthogonallyto forwardly and rearwardly) of an upper end of the swing arm 18, andthe swing arm 18 is attached in a forwardly and rearwardly swingingmanner to the moveable body 12 via the rotational shaft 21. Loadapplying device 22A for applying resistance to rotation of therotational shaft 21 is installed within the moveably body 12. The loadapplying device is comprised of a braking shaft 23 equipped with anelectromagnetic brake 22 taken as braking means and an acceleration gear24 meshing with the braking shaft 23. Strength applied to the rotationalshaft 21 by the electromagnetic brake 22 can be varied by instructionsfrom the controller 28. Load applying device for braking of the swingarms 18 is by no means limited to using magnetic brakes and otherbraking means may also be adopted.

A rotary encoder 26 for detecting rotation angle and rotational speed(including rotation direction) is arranged within the moveable body 12.The rotation angle and rotational speed of the rotational shaft 21 aredetected in accordance with swing movement of the swing arm 18 forwardlyand rearwardly. The detected information is then transmitted to thecontroller 28 and a drive instruction is transmitted from the controller28 to the servo motor 13. The ball screw 14 is then driven and themoveable body 12 is made to move forwardly and rearwardly in synchronismwith the swing movement of the swing arm 18.

Specifically, a starting point for the angle of the swing arm 18(rotational shaft 21) is such that the swing arm 18 extends in asubstantially vertical direction (state in FIG. 2, FIG. 10 and FIG.11B). When the swing arm 18 then swings forwardly (the state in FIG. 4and FIG. 11A), the angle becomes positive, and when the swing arm 18swings rearwardly (the state in FIG. 6 and FIG. 11), the angle becomesnegative.

At the time that the swing arm 18 swings forwardly, the servo motor 13is driven via the controller 28 based on detection results for rotationof the braking shaft 21 of the rotary encoder 26 and the moveable body12 is made to move rearwardly at a prescribed speed. At the time thatthe swing arm 18 swings rearwardly, the servo motor 13 is driven via thecontroller 28 based on detection results for rotation of the brakingshaft 21 of the rotary encoder 26 and the moveable body 12 is made tomove forwardly at a prescribed speed.

A torque meter 27 is provided within the moveable body 12. The torquemeter 27 acquires rotation torque (power data) for the braking shaft 23(rotational shaft 21) using rotation of the gear 25 meshing with thebraking shaft 23, and sends the acquired power data to the controller 28and computer 31.

FIG. 12 is a view illustrating control of the exercise device of thepresent invention. The operation of the exercise device is controlled bythe controller 28. Strength adjustment of load resistance with respectto rotation of the swing arm 18, adjustment of driving of movement ofthe moveable body 12 forwardly and rearwardly and of the movement speed,and adjustment of the height of the moveable body 12 are carried outbased on output instructions from the controller 28. Input to thecontroller 28 is carried out using information acquired from a rotaryencoder 26 constituting detection means monitoring rotation of the swingarm 18 and the torque member 27, and input from the operation unit 30.

When the angle and speed of the rotational shaft 21 are received fromthe rotary encoder 26, the controller 28 outputs an instruction to theservo motor 13 and the moveable body 12 is moved at a prescribed speed.When an input to adjust height of the moveable body 2 is received fromthe operation panel 30, the controller 28 outputs an instruction to alinear actuator 17 and the support member 15 supporting the guidemembers 11 on which the moveable body 12 slides are caused to move in avertical direction. When input strength of the load resistance withrespect to the rotational shaft 21 is received from the operation panel30, the controller 28 provides a prescribed load resistance to therotational shaft 21 via the electromagnetic brake 22. The controller 28is therefore constructed from a load strength adjustment apparatus,height adjustment apparatus, and movement speed adjustment apparatus.

Further, each type of information (for example, angle, power, speed) issent to a computer 31 electrically connected to the controller 28 and isstored in a storage unit of the computer 31. If necessary, theinformation is analyzed by an arithmetic unit of the computer 31, andstored information or calculated information is displayed at a displayunit of the computer 31 as necessary.

A description is given of an exercise operation employing exercisedevice of the above configuration based on FIG. 11. FIG. 11B shows startconditions, with the swing arms 18 being substantially vertical withrespect to the floor when a person exercising holds operation in astanding position. The fulcrum of rotation (rotational shaft) of theswing arm 18 can be adjusted to the height of the lower end of thesternum of the person exercising by adjusting the position of the heightof the moveable body 12. As a result, forwardly and rearwardly movementof the swing arm 18 enables a swing operation of the leg and waist ofthe same side taking the height of the flank of the person training asan axis. The positions of the pads 19 attached to the swing arm 18 andthe support arm 20 are adjusted, and the pads 19 are adapted to sandwicha leg (the left leg in the drawings), and a pendulum-like movement ofthe swing arm 18 is implemented in accordance with a forwardly andrearwardly swing operation of the leg from a standing operation.

From the state in FIG. 11B, the hand rails 29 are grasped with bothhands. When the thigh of the left leg is then lifted up forwardly, theswing arm 18 swings forwardly and an inclined posture is adopted. Therotation angle and speed of the rotational shaft 21 of the swing arm 18is then detected by the rotary encoder 26. By then sending thisinformation to the controller 28, the servo motor 13 is driven accordingto instructions from the controller 28, and the fulcrum of rotation(rotational shaft 21) of the swing arms 18 moves forwardly (FIG. 11A) inaccordance with the moveable body 12 moving rearwardly in synchronismwith the swing movement of the swing arm 18 forwardly.

From the state in FIG. 11B, when the thigh of the left leg is thenlifted up rearwardly, the swing arm 18 swings rearwardly and an inclinedposture is adopted. The rotation angle and speed of the rotational shaft21 of the swing arm 18 is then detected by the rotary encoder 26. Bythen sending this information to the controller 28, the servo motor 13is driven according to instructions from the controller 28, and thefulcrum of rotation (rotational shaft 21) of the swing arm 18 movesforwardly (FIG. 11C) in accordance with the moveable body 12 movingforwardly in synchronism with the swing movement of the swing arm 18rearwardly.

According to this apparatus, it is possible to cause the swing arm 18 toswing so as to work the muscles such as the psoas major and the iliacusby adjusting the fulcrum of rotation (rotational shaft 21) of the swingarm 18 to the height of the twelfth thoracic vertebrae and operating theleg and waist at the same time.

The exercise device of the present invention is provided with anoperation panel 30 at the top of the front of the frame. The operationpanel 30 is constructed from a touch panel. Input from the operationpanel 30 is sent to the controller 28 and each operation is thencontrolled via the controller 28. In the initial state, it is possibleto adjust the position in a direction from front to rear of the moveablebody 12 and the vertical position of the moveable body 12 at the time ofstarting by operating each of the various touch-buttons on the operationpanel 30. For example, in the event that it is wished to move theposition in a direction from front to rear of the moveable body of theleft side slightly forwardly, it is possible to move the moveable body12 of the left side along the guide member 11 slightly in a horizontaldirection towards the front via the controller 28 and driver 13 bycontinually pressing the forward button switch of the left unit.Further, in the event that it is wished to move the vertical position ofthe moveable body 12 of the left side slightly upwards, it is possibleto move the moveable bodies 12 of the left side slightly upwards via thecontroller 28 and driver 17 by continually pressing the up button switchof the left unit.

The operation pane includes an exercise setting screen. Load setting(deciding load of stroke forwardly and rearwardly), arm selection(selection as to whether to exercise using the left leg or the rightleg), and mode selection (selection of M mode, S mode) may be includedin the exercise setting procedure. The electromagnetic brake 22 iscontrolled via the controller 28 based on load settings inputted fromthe operation panel 30. Here, M mode refers to a mode of moving thefulcrum of rotation in accordance with swinging of the swing arm 18during training. S mode refers to a mode where the fulcrum of rotationdoes not move according to swinging of the swing arm 18 during training.In this mode, the forwardly and rearwardly movement of the moveable body12 is locked. In the event that S mode is selected, the swing arm 18swings forwardly and rearwardly in a state where the fulcrum of rotationis fixed.

When the exercise setting is complete, an exercise start screen isdisplayed at the operation panel 30. If a right angle lamp or a leftangle lamp flashes green (this is a lamp for making it known when theangle of the arms is in a state where the exercise can be started), theexercise can be started by pressing the exercise start switch.

Each type of information is monitored and displayed in real time duringexercise and this information can be stored in the storage unit of acomputer. After training is complete, the exercise results are displayedat the operation panel 30. In addition to working the muscles such asthe psoas major and the iliacus, the exercise device of the presentinvention is also capable of calculating and measuring muscular powerand exercising power used to work the muscles.

1. An exercise device comprising a swing arm defining a fulcrum ofrotation, the swing arm moveable forwardly and rearwardly via thefulcrum of rotation, wherein the fulcrum of rotation of the swing arm isreciprocally moveable forwardly and rearwardly such that the fulcrum ofrotation moves rearwardly when the swing arm swing forwardly and thefulcrum of rotation moves forwardly when the swing arm swingsrearwardly.
 2. The exercise device of claim 1, wherein the fulcrum ofrotation of the swing arm is coupled to a moveable body capable ofreciprocal movement forwardly and rearwardly.
 3. The exercise device ofclaim 2, wherein the exercise device is provided with a forwardly andrearwardly extending guide member, and the moveable body is guided bythe guide member so as to move forwardly and rearwardly.
 4. The exercisedevice of claim 2, wherein swinging of the swing arm and movement of themoveable body is synchronized.
 5. The exercise device of claim 4,further comprising a detector for detecting swinging of the swing arm, adrive for moving the moveable body, and a controller for controllingmovement of the moveable body.
 6. The exercise device of claim 5,wherein the swing arm may also swing via a rotational shaft, and thedetecting means detects the angle and speed of the rotational shaft. 7.The exercise device of claim 2, wherein load applying device forapplying load to rotation of the swing arm is provided at the moveablebody.
 8. The exercise device of claim 3, wherein the height of thefulcrum of rotation of the swing arm is adjustable.
 9. The exercisedevice of claim 8, wherein the guide member is vertically moveable, andadjustment of the height of the fulcrum of rotation of the swing arm iscarried out by adjusting the height of the guide member.
 10. An exercisedevice comprising: a swing arm having a rotational shaft, the armcapable of swinging forwardly and rearwardly via the rotational shaft; amoveable body provided with the rotational shaft, the moveable bodycapable of reciprocating forwardly and rearwardly; a drive for movingthe moveable body forwardly and rearwardly; a detector for detectingrotation angle and rotation speed of the rotational shaft in accordancewith swinging movement of the swing arm; and a controller forcontrolling movement of the moveable body in accordance with therotation angle and rotation speed of the rotational shaft detected bythe detector, wherein the drive is driven via the controller so as tomove the moveable body rearwardly when a swing arm swings forwardly, andthe drive is driven via the controller so as to move the moveable bodyforwardly when the swing arm swings rearwardly.
 11. The exercise deviceof 10, wherein the exercise device is provided with a forwardly andrearwardly extending guide member, and the moveable body is guided bythe guide member so as to move forwardly and rearwardly.
 12. Theexercise device of claim 10, the apparatus further comprising loadapplying device for applying a load with respect to rotation of therotational shaft.
 13. The exercise device of claim 10, wherein theheight of the fulcrum of rotation of the swing arm is adjustable. 14.The exercise device of claim 13, wherein the guide member is verticallymoveable, and adjustment of the height of the fulcrum of rotation of theswing arm is carried out by adjusting the height of the guide member.15. An exercise device to simulate a leg swing motion, comprising: aframe; at least one longitudinal guide supported by the frame; at leastone moveable body reciprocally moveable along the guide, the moveablebody having a pivot axis defined thereon; and at least one swing armpivotally coupled to the moveable body about the pivot axis such thatthe moveable body moves rearwardly when the swing arm swings forwardlyby a forwardly leg swing motion and the moveable body moves forwardlywhen the swing arm swings rearwardly by a rearwardly leg swing motion.16. The exercise device of claim 15, wherein said swing arm has aportion contacting a leg and the portion travels along a U-shaped pathof travel with forward and rearward leg swing motion.
 17. The exercisedevice of claim 15, said device further comprising: a drive for movingthe moveable body along the guide; a detector for obtaining informationon swinging movement of the swing arm; and a controller for controllingthe drive in accordance with the information.
 18. The exercise device ofclaim 16, wherein said information includes rotation angle and rotationspeed of the pivot shaft.
 19. An exercise machine comprising: at leastone swing arm having an axis of rotation, the swing arm swingingforwardly and rearwardly by forward and rearward leg swing motion;wherein the axis of rotation is reciprocally moveable forwardly andrearwardly such that the axis of rotation moves rearwardly when theswing arm swing forwardly and the axis rotation moves forwardly when theswing arm swings rearwardly.